There is an increasing proliferation of electric charging stations for electric vehicles. Electric vehicles within the meaning of this subject matter can, by way of example, be purely electrically operated vehicles or what are known as plug-in hybrid vehicles, both of which have a battery which can be electrically charged. Charging stations are generally positioned in public and semi-public areas, in order to be available to the general public. In the expansion of the charging stations infrastructure, the safety of such charging stations is of increasing relevance. Both with direct current (DC) and alternating current (AC) charging, electrotechnical safety aspects must be considered. Non-hazardous operation of the charging stations must always be ensured. It must in particular be ensured that the user is protected from an electric shock harmful to health.
To this end, conventionally what are known as fault current switches have been provided in charging stations. Monitoring of an ground fault may be provided for as an alternative or in addition. These protective circuits prevent a user who comes into contact with live components of the charging station suffering from an electric shock harmful to health. Here the safety switches ensure that in the event of an ground fault and/or a fault current, the electrical line is interrupted.
In the event of a short circuit also, that is to say at high currents, the charging station must be able to switch off. For this purpose, so-called contactors are provided which even under high load can safely switch off a current. With the help of the contactors the mains connection of the charging station is isolated from the other electronics within the charging station.
Apart from the stated safety aspects, further safety-related devices can be provided in charging stations, which monitor the electrical functions of the charging station and in the event of a fault either isolate the electrical line themselves or output a corresponding isolation pulse.
In known charging stations, however, the respective safety-related devices are operated autonomously and independently of one another. This means that no higher-level monitoring of the functioning of the individual safety elements exists. As a result, there are safety risks in the event of a malfunction of individual safety elements.